The Pennsylvania Supreme Court invalidated the existing map last month as an unconstitutional gerrymander, ruling that Republican lawmakers had marginalized Democratic voters in an effort to win more seats in the U.S. House of Representatives.

A new map is expected to boost Democrats' chances of winning more Pennsylvania seats in November's midterm elections, when they need 24 nationwide to take control of the House from Republicans. Republicans hold 13 of the state's 18 congressional seats despite Pennsylvania's status as a closely contested swing state.

"The analysis by my team shows that, like the 2011 map, the map submitted to my office by Republican leaders is still a gerrymander," Wolf said in a statement. "Their map clearly seeks to benefit one political party, which is the essence of why the court found the current map to be unconstitutional."

The court's Democratic majority had given Wolf until Thursday to decide whether to accept or reject the new map submitted by Republican leaders late on Friday. With no deal in place, the court has said it will undertake the process of drawing new lines itself, with help from an independent redistricting expert.

Legal battles are playing out in several U.S. states over partisan gerrymandering, the process by which district lines are manipulated to favor one party over another. Pennsylvania has long been seen as one of the worst offenders, with one of its more oddly shaped districts described derisively as "Goofy Kicking Donald Duck."

Leaders in the Republican-controlled state legislature have said they may file a federal lawsuit challenging the state Supreme Court's authority to draw the map. The U.S. Supreme Court last week rebuffed an emergency appeal filed by Republicans.

Any new map would likely result in sitting Congress members, candidates and thousands of voters finding themselves living in a new district. The primary midterm elections are scheduled for May.

The state Supreme Court's order called for a map that prioritized compactness and avoided splitting counties and municipalities. Numerous redistricting experts have said in recent days that the proposed map remains heavily gerrymandered, despite creating more compact districts.

Wolf's office retained Moon Duchin, a mathematician from Tufts University, to analyze the Republican proposal. In a statement, Duchin said she calculated there was no more than a 1-in-1,000 chance that a map drafted to comply with the court's order would result in such a large advantage for Republicans.

"The proposed Joint Submission Plan is extremely, and unnecessarily, partisan," she said.

In a 5-2 decision along party lines, the court struck down the existing map on Jan. 22, ruling on a lawsuit filed last year by Democratic voters and the League of Women Voters of Pennsylvania. The court found that the current lines violate the state constitution's free speech and equal protection guarantees by depriving Democratic voters of meaningful ballots.